Abstract
Lactiplantibacillus plantarum could regulate certain physiological functions through the AI-2/LuxS-mediated quorum sensing (QS) system. To explore the regulation mechanism on the growth characteristics and bacteriostatic ability of L. plantarum SS-128, a luxS mutant was constructed by a two-step homologous recombination. Compared with ΔluxS/SS-128, the metabolites of SS-128 had stronger bacteriostatic ability. The combined analysis of transcriptomics and metabolomics data showed that SS-128 exhibited higher pyruvate metabolic efficiency and energy input, followed by higher LDH level and metabolite overflow compared to ΔluxS/SS-128, resulting in stronger bacteriostatic ability. The absence of luxS induces a regulatory pathway that burdens the cysteine cycle by quantitatively drawing off central metabolic intermediaries. To accommodate this mutations, ΔluxS/SS-128 exhibited lower metabolite overflow and abnormal proliferation. These results demonstrate that the growth characteristic and metabolism of L. plantarum SS-128 are mediated by the AI-2/LuxS QS system, which is a positive regulator involved in food safety. It would be helpful to investigate more bio-preservation control potential of L. plantarum, especially when applied in food industrial biotechnology.
Highlights
Lactic acid bacteria (LAB) comprise a huge group of safe and widespread microorganisms in nature, and they are primarily applied as starter cultures and probiotics [1,2].LAB are apprehended as ideal candidates for commercial exploitation in food industry with their status recognized as Generally Regarded As Safe (GRAS) and Qualified Presumption of Safety (QPS) in the European Union [3,4]
Since the above results showed that AI-2/LuxS positively regulated the bacteriostatic activity and growth of L. plantarum SS-128, to explore the correlation between two regulatory networks, the metabolome and transcriptome data were subjected to integrated analysis
The comparative multiomic analyses demonstrated that the higher pyruvate metabolic efficiency and energy input, followed by higher Lactate dehydrogenase (LDH) level and metabolite overflow in SS-128, resulted in stronger bacteriostatic ability compared to that of ∆luxS/SS128
Summary
Lactic acid bacteria (LAB) comprise a huge group of safe and widespread microorganisms in nature, and they are primarily applied as starter cultures and probiotics [1,2].LAB are apprehended as ideal candidates for commercial exploitation in food industry with their status recognized as Generally Regarded As Safe (GRAS) and Qualified Presumption of Safety (QPS) in the European Union [3,4]. Aside from the health-promoting and probiotic properties, certain LAB producing organic acids, including lactic acid and phenyllactic acid (PLA), are associated with food industrial biotechnology, providing food preservation for biocatalysis [5,6,7,8,9]. Strategies of enhancement on bio-preservation potential can be roughly classified into two major types: the strain development strategy and microbiological control strategy. The microbiological control strategy involves the regulation of LAB to microorganisms throughout the food system or environment. Both strategies are regulated by quorum sensing (QS), which provides new opportunities to enhance the safety and quality of foods by the “positive regulation” of QS
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